The use of focused light from an axial high-pressure lamp for the treatment of various diseases of the retina, e.g., diabetic retinopathy, by means of the light coagulation has been known for decades. Nowadays, the retina is warmed up or coagulated during light coagulation by means of a laser beam, wherein the energy of the laser beam is absorbed by the dark coloring of the pigment epithelium within the retina. As a result, the metabolism is focused on the as yet healthy areas of the retina. In addition, biochemical cofactors are stimulated. This way, the progress of the disease is considerably slowed or stopped.
However, it is hereby disadvantageous that tissue worthy of preservation, particularly the photoreceptor layer located in beam direction in front of the retinal pigment epithelium, is also destroyed. Therefore, solutions have been provided which minimize the destruction of tissue worthy of preservation, wherein the local treatment is terminated once a defined temperature is reached at the coagulation point. Hereby, a temperature-controlled coagulation system with a continuous coagulation laser and a pulsed measuring laser as well as a detector, a control device, and an interrupter is used. Thereby, the coagulation laser is designed is such a way that a coagulation beam is emitted and that the measuring laser generates a temperature-dependent measurement signal for the detector in the target area of the coagulation laser. Thereby, the detector exhibits a temperature sensor that detects a signal which allows for conclusions regarding the temperature at the coagulation point. The signal detected by the detector is transmitted to the control device which activates the interrupter once a predetermined temperature is reached, thereby interrupting the beam of the coagulation laser.
The coagulation points are periodically adjusted manually by the operator who individually triggers the coagulation beam. This is very time-consuming and the success of the treatment greatly depends on the abilities of the operator; therefore, it was suggested in WO 2007/035855 A2, e.g., to provide a system and a method, wherein a pattern of coagulation points is provided from which the operator can choose beforehand and/or combine the various patterns with one another. Thereby, two-dimensional arrangements of coagulation points are considered patterns which, for example, exhibit a matrix of 2×2, 3×3, 4×4, 5×5, etc., wherein the distances of adjacent coagulation points remain constant. This prior art also provides other two-dimensional patterns, e.g., arrangements on a circle and/or on concentric circles, elliptical and sector-shaped arrangements.
However, such fixed patterns of regular geometry are disadvantageous because very often they do not correspond to the morphological conditions of the physiological anomalies. Therefore, recoagulation with a second or third coagulation pattern up to a single-burst coagulation, which was to be overcome with said method, is frequently required for efficiently executing a completely effective panretinal photocoagulation. Even though it is possible with the above-mentioned prior art to achieve a large pattern which leads to an increase in the speed of the treatment, the risk of overcoagulation and/or undercoagulation through the changeable focus remains due to the retinal curvature and/or varying absorption behavior of the present ocular media.